Electrostatic Analysis of AlN/GaN HEMTs Using β-Ga2O3 Buffer on SiC and β-Ga2O3 Wafers for 5G/6G Wireless Infrastructure and Future Sub-THz Applications
摘要
In this work, a recessed T-gated AlN/GaN-HEMT with a β-Ga2O3 buffer is proposed and compared with conventional buffer configurations, including Fe-doped GaN/AlGaN structures with and without back-barriers (BBs), to evaluate their influence on direct-current (DC) and radiofrequency (RF) performance. The electrostatic analysis of HEMT with β-Ga2O3-buffer reveals a peak gm of 431.5 mS/mm, an Id_peak of 1.90 A/mm, an Ids_sat of 2.42 A/mm, and an fT of 197.1 GHz owing to better carrier confinement, reduced parasitic effects, minimal buffer leakage, and the high crystalline quality of the β-Ga2O3/GaN interface. We investigated the impact of barrier material selection and observed that an AlN barrier offered better performance, attributed to stronger polarization-induced charge, followed by Al0.83In0.17N, and AlxGa1−xN, with a gradual decline as the Al composition decreased. The AlN/GaN/β-Ga2O3/β-Ga2O3-HEMT with Lg = 40 nm delivered a maximum gm of 538.5 mS/mm, an Id_peak of 3.22 A/mm, and an fT of 469.6 GHz, along with an Ids_sat of 3.49 A/mm, benefiting from improved lattice compatibility. Notably, this structure eliminates the need for additional BB layers and AlN nucleation, offering both performance and fabrication advantages. The AlN/GaN/β-Ga2O3/SiC-HEMT also delivered competitive performance, providing a compelling combination of thermal conductivity, material stability, and integration feasibility, while remaining cost-effective. These results offer valuable design insights for AlN/GaN-HEMT development and contribute to ongoing efforts toward enhancing GaN-HEMT performance through the integration of ultrawide bandgap (UWBG) β-Ga2O3 buffers, making it highly suitable for next-generation 5G/6G wireless infrastructure, sub-THz high-speed communication systems, and advanced radar applications.